Liquid vessel liner and method of application

ABSTRACT

A liner and method of application for use on a metal surface to protect metal structures such as cooling towers, evaporative condensers, and other liquid containing vessels such as tanks from corrosion, leaks, and wear. The liner is an inexpensive apparatus and process comprising a coated metal having a second sealing and bonding layer and a third protective sealing layer. The liner method comprises applying an organic bonding layer onto the galvanized substrate, and applying an elastomeric barrier coating to the bonding layer. The barrier coating material is applied to preseal the seams between adjoining panels assembled to form the basin. The barrier coating is applied to the entire inside of the basin to form a homogenous barrier coating extending out of the basin. The liner edge is isolated from the basin by extending the liner to a point between the basin and an upper section. The liner comprises galvanizing layer, a bonding layer on the galvanized metal, and an elastomeric third layer on the bonding layer. The liner further comprises preseals at the seams, corner molds and link holes in the substrate to attach and protect the liners integrity.

BACKGROUND OF THE INVENTIONS

The present invention relates to liners bonded to liquid containingmetal structures and the method of applying and bonding the liner.

DESCRIPTION OF THE RELATED ART

Liquid holding structures such as cooling towers, evaporativecondensers, and other evaporative systems for cooling or condensing andholding evaporative liquid are subjected to great mechanical stressesand exposure to corrosive environments. Chemicals used in the water tocontrol water chemistries and to prevent biological growth can also workagainst the metal structure sections to promote corrosion unlesscarefully monitored. Such structures are usually made of treated steel,stainless steel, or plastic to protect the basin from corrosion. Plasticor polymer structures may be made from FRP or Polypropylene or similarmaterials. Fasteners are used to attach the panels together. The seamsbetween the panels are usually sealed separately to give addedprotection to these areas. These metal structures are more likely toleak at or around the seams. Seams are sealed with a butyl rubber tapeand/or a caulk. Prior art systems involved the use of galvanized,plastic or stainless materials to hold the liquid and prevent corrosion.Galvanized basins and structures provide limited resistance tocorrosion. Prolonged exposure, especially to treated water having highchlorides and the like, can break down the galvanized coating. The lossof the galvanized coating exposes the panels to the corrosive liquidresulting in a need to repair or replace the structure or sections.Stainless tanks and basins are expensive and may be susceptible tocorrosion from certain water chemistries such as high chlorides. Vesselsformed from galvanized panels use many more fasteners than are needed tostructurally assemble the panels. The fasteners are positioned andinserted to seal the seams as well as hold the panels together. Thefasteners may need a fastener hole formed in the aligned flanges.Stainless steel panels can be fastened together with to form the basinor vessel having good corrosion protection to some chemicals.Furthermore, most metal vessels also have square corners and jointsmaking vessel cleaning difficult and drainage an issue as water can poolin a corner or at an angle joint.

Single or multi piece plastic or polymer basins are susceptible tocracking, and may not be structurally sound when containing largevolumes. The plastic structures may be flammable, expensive, and damagedby heat or thermal shifts due to climates that have wide temperaturerange swings. Coatings such as epoxy and polymer coatings on metal haveweaknesses especially when the coating is below the water line andexposed to chemicals and the water continuously. Such exposure canresults in blistering, cracking, and peeling of the coating and thusexposing the metal substrate to the water and chemicals. Lining thebasins with materials such as polyurethane may be difficult because oflong cure times and expensive surface preparation. The lined basins arestill susceptible to compatibility with sealer material like tape,caulk, and other sealants used which may react with the barrier coatingafter installation. Furthermore, the polyurethane liners are known toflow through cracks and seams in their liquid state before curingcausing uneven coating especially where the liner is needed most, at theseams. Adhesion of the liner to the substrate can also be a problemespecially on the bottom and walls below the water level. Water andchemicals attacking the edge interface between the liner and thesubstrate can penetrate between the liner and the substrate causingcorrosion behind the liner. This corrosive damage can be very hard torepair and may damage the integrity of surrounding areas.

Steel structures have been used extensively in the prior art to buildstructures for holding liquid such as water and treated water forcooling and evaporative functions. A steel structure provides acost/strength-valued construction, but must be insulated from theliquid. Those skilled in the art would recognize that the prior artteaches that corrosion protection is accomplished with a polymer coatingthe structure or an organic powder coating. Each coating requiresseveral steps be satisfied. First, the surface must be thoroughlycleaned of all dirt, oil, oxidation products, and any other foreignmatter. Second, sites to which the liner can bond must be available onthe surface. Third, the coatings must be specially formulated to impartspecific wear, adhesion, sealing, and corrosion resistant properties tothe steel when applied in layered sequential coatings. Liner joints orseams below the water line can allow penetration of the liquid throughthe seam and behind the liner promoting corrosion and eventually causinga leak.

The U.S. Pat. No. 4,540,637 to Geary et al. for a PROCESS FOR THEAPPLICATION OF ORGANIC MATERIAL TO GALVANIZED METAL is assigned to theassignee of the present invention and the disclosure is by thisreference incorporated in its entirety in the present application. Theliner protects the surface of the panels from chemical attack andcorrosion caused by the water, treated water or other liquid containedin the vessel.

The '637 patent discloses and claims a process for the application of anorganic powder coating to galvanized steel comprising a four stepprocess. The panels are acid cleaned to remove contaminates andthoroughly rinsed and dried to prepare the metal galvanized surface foradhesion of the powder coating. The powder coating uses the galvanizedlayer as a back up corrosion resistant layer to protect and supplementespecially where the panels are physically damaged in use destroying aportion of the powder coating.

The prior art also includes roll-on and spray on liners for applicationto the interior walls of a vessel. These “after market” liners do notadhere well to the substrate due to contamination and corrosion on thesurface of the metal. These “after market” liners are more expensive toapply because of surface preparations and labor required forinstallation. In addition, these prior art liners use cleaners, primercoatings, and/or mechanical surface preparation such as sanding, sandblasting or the like to clean and prepare the surface. Sealants used toseal the seams are butyl tape and/or caulk and may react chemically withthe liner and may create a loose attachment of the liner to thesubstrate causing a compromised installation.

SUMMARY OF THE INVENTION

The present invention is a factory-installed liner for use inevaporative cooling, condensing and similar systems holding andcirculating hot and cold liquids for heat transfer and storage. Theliner includes a coated metal such as galvanized steel as a structuralsubstrate having a powdered polymer coating electrostatically appliedand baked on the clean galvanized surface. The organic powder polymerbonds chemically and mechanically to the galvanized metal substrate andprovides a clean, dry and possibly warm surface for the elastomericbarrier coating to mechanically and chemically adhere to. Additionalsupport is provided for the barrier coating by holes formed in thesubstrate panels of the structure, forms placed in the corners, lineredges isolated from contact with flowing or standing water and seamsattached without caulks and sealants. The holes are formed prior toapplication of the organic powder. The organic powder is applied to flowthrough sealing the hole and the surrounding galvanized material on theinside and outside surfaces. The forms provide better drainage toprevent standing water when the vessel is not in use. The forms are forallowing draining along the vessel edges where dirt, debris, andcorrosive elements may become trapped and stand degrading the barriercoating. The panels are attached using mechanical fasteners in thestandard manner of connecting panels to form a contiguous vessel wall.Fasteners are used in assembling the panels. The caulk or tape used inthe prior art for sealing all sides with a homogenous application orsealing the seams are not used in the present invention. The presentinvention describes and claims a liner and method of application forsealing the seams and lining the panels with a homogenous application ofan elastomeric material requiring fewer fasteners used and fewer holesin assembling the panels.

The present invention is directed to a liner for use on the innersurface of a vessel or basin comprising a first coating of zinc appliedto the steel panels to galvanize them. A second coating comprises anorganic powder coating on the galvanized coating and a third layer of amaterial such as polyurethane, polyurea, a polyurethane/polyurea blend,or similar. The organic powder is applied electrostatically to provide auniform and even coating even in blind spots to a clean galvanized steelsurface and baked to cure resulting in a sealing coat having goodadhesion and providing a bonding surface for the third polyurethanebarrier coating layer. The organic powder coating may be an epoxy-likematerial such as deposited by the Baltibond Corrosion Protection Systemavailable from Baltimore Air Coil and described and claimed in theaforementioned U.S. '637 patent. The organic coating is applied to theinterior and exterior surfaces in the manufacture of the structure by amulti-step cleaning and drying process to maximize adhesion between thecoating and the metal. The coated panels are assembled using threadedfasteners or rivets as is known in the art of mechanical assembly of alarge metal vessel or structure. The method of the present inventiondoes not require a separate sealing tape or sealant before applicationof the third barrier coating layer. The method includes applying theelastomeric material in liquid form over the seams and any portion ofthe fasteners exposed to the inside of the vessel. In the double breakflange assembly of the vessel; all fasteners are typically outside thebasin as shown in FIG. 2. In all cases in the present invention, theseams are covered by liquid barrier coating material first to provide apreseal. The method can also further comprise placing of corner forms inthe corners and/or at the angled areas where the panels meet or bend topromote drainage and cleaning of the vessel, forming an inner surfacewith smooth transitions. The barrier coating is sprayed over the entirevessel interior up to and over the maximum standing water level. Thebarrier coating extends past the junction point for an adjoining panelto provide for the adjoining section to be connected having the seamisolated from the standing water. Often this seam can be further securedby compressing the barrier coating between the flanges or use of aflange ring wherever possible.

The present invention is directed to a liner mechanically coupled to thekey areas of the vessel such as sidewalls, high flowage areas and areasof high traffic. The mechanical coupling to the panels is achieved bypunching link holes in the panels to allow the powder coating to coat inaround and through each hole without closing the opening in the panel.The link holes allow the elastomeric barrier material to flow out of thelink hole and form a button-like globule on the outside of the vesseltied to the barrier coating. The elastomeric barrier coating extendsfrom the inside of the vessel to the outside of the panel through thelink hole to mechanically attach the barrier coating to the sidewall.The clean dry surface of the organic powder second sealing layer allowsthe atomized spray of the elastomeric third layer to penetrate the poresand mechanically and chemically attach to the substrate. The organiccoating over the galvanized steel provides a second protective layer aswell as a bonding layer, and the sealing barrier coating provides atriple level of protection for the metal structure. The barrier coatingis an inert material that resists corrosive water conditions andchemicals in the water better than stainless steel, especially in highchloride environments.

The present invention is directed to a process for assembling andsealing a cooling tower, water basin or the like for holding water forcooling, evaporative or condensing systems. The process comprises thesteps of forming panels in preconfigured shapes and sizes. The operatorpunches holes in the panels in a predetermined pattern, the holes spacedfrom the edges of the panel for further attachment of the barriercoating. The panels are galvanized steel of a type G-235 to provide afirst corrosion resistant coating. The number following the Gdesignation refers to the total coating weight on both sides of thesheet in hundredths of an ounce per square foot (oz/ft²) of sheet. Thus,G235 would have a minimum total 02.350 oz/ft² of coating. The panelscomprise a pre-adapted collection of steel panels for assembly into aholding basin. The panels are cleaned by an acid type cleaning solutionsuch as phosphoric acid to remove contaminates followed by a rinse withwater to remove the cleaner. The next step is to rinse again to insurethe acid solution is removed. Next, the operator dries the panels usingair and heat to thoroughly dry the metal and immediately thereafter coatthe panels with an organic powder coating such as, for example epoxy,polyester, acrylics or hybrids that are homogenous and designed forapplication to metals. The powder is applied by electrostatic spray onboth sides of the panel especially around the link holes and edges to atypical thickness of 0.004 inches. The coated metal panels are bakedusually at around 250-600 degrees for 1 to 20 minutes to thermoset thepowder coating 56. The time and temperature are predetermined valuesdepending on the coating and thickness of the steel to cure the coating.The panels are cooled after curing and the clean and coated panels areassembled into subassemblies for application of the barrier coating. Theelastomeric barrier coating application steps comprise, first applyingin a liquid state, directly over the seams to form a preseal for theseams and prevent the elastomeric material from leaking through theseams during application. Next, the forms, if desired, are placed in thecorners and where adjoining panels meet; next spraying the elastomericmaterial onto the basin including double spraying the seams and anyexposed fasteners. The barrier coating coats the interior of the vesseland extends out of the basin and over the basin flange such that thebarrier coating extends above the maximum standing liquid level andbeyond the attachment to the upper structural section.

The present invention is directed to an elastomeric barrier coating thatis double applied over seams and fasteners and extends from in theliquid holding area to outside the liquid holding area by application tothe basin and extension along the mounting flange of the basin to apoint separated from the inside of the basin by the attachment of theadjacently upper panel attaching to the basin with the liner edgebetween the respective mounting flanges where possible. Additionalattributes of the elastomeric barrier coating include extension of thebarrier coating outside the basin, link holes punched in the panelsforming a mechanical link to the panel by a button-like knob of barriercoating material formed on the outside of the basin by the liquidelastomeric material flowing out of the link hole and hardening. Thelink seals the adjacent link hole. The elastomeric barrier coating maybe selected from elastomeric coatings and appropriate additives havingacid resistance, fast cure times, inert properties, high durability,fire retardancy, and/or ablative properties.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation section view of a prior art seam sealed withtape and caulk over the fasteners and seams;

FIG. 2 is a side elevation section view of a basin seam sealed inaccordance with the present invention;

FIG. 3 is a side elevation section view of a pre-sealed and lined basinsubassembly in accordance with the present invention;

FIG. 4 is a section view of a mechanical link between the barriercoating and the basin panel in accordance with the present invention;

FIG. 5 is a side elevation section view of a connection pipe in thebasin in accordance with the present invention;

FIG. 6 is a side elevation section view of the mechanical lock on thebarrier coating edge between the basin and the upper section inaccordance with the present invention;

FIG. 7 is a section view of a panel coated and lined in accordance withthe present invention;

FIG. 8 is a flow chart demonstrating one method of lining a liquidholding basin in accordance with the present invention;

FIG. 9 is a side section view of an assembled structure showing thelined basin and the lined upper section with the respective barriercoating edges captured between the adjoining flanges.

DETAILED DESCRIPTION

The prior art basin of FIG. 1 shows a basin 10 made of panels 12fastened together at the edges 14 of the panel 12. The panels 12 areconfigured to form a water holding basin 10 having a bottom 30 with anouter edge attached to panels 12 adapted to form a side wall 32. Thebasin 10 has a bottom 30, a side wall 32. Fasteners 16 extend throughthe flanges 42 to hold the panels 12 together to form a structure suchas a basin 10. The fasteners 16 may be self-tapping sheet metal screwsor nut and bolt assemblies depending on individual basin requirements.The number of fasteners 16 is calculated to hold the panels 12 togetherstructurally and for sealing purposes. The fasteners 16 extend throughmating fastener holes 18 in adjacent flanges 40 as is well known in theart of assembling panels together into a basin 10 or the like. In theprior art vessels, a sealing tape 20 may be used to seal the seam 24between panels 12 and a caulk 22 may be used over the seal tape as asecondary sealing measure.

Referring to FIG. 2, the panels 12 are joined together at flanges 40having a fastener portion 42 directed away from the basin 10. The breakflanges 40 have the fasteners 16 outside the basin 10 through theflanges 40, also called break flanges 40, to hold the panels 12together. In accordance with the present invention, the elastomericbarrier coating 26 is applied in liquid form to the seams 24 between thepanels 12 to form a pre-seal 25. The elastomeric barrier layer 26materials flows into the seam 24 between the adjacent panels 12 to filland seal the seam 24 and form a pre-seal 25 over and in each panel seam40.

Continuing to refer to FIG. 2, the basin 10 is lined with an elastomericbarrier layer 26 applied in a continuous coat over the fasteners 16 andthe seams 24. Corner molds 28 are positioned to smooth the transition atcorners such as where the bottom panel 30 meets the lower most sidepanel 32. These corner molds 28 have a bottom wall 34, a sidewall 36 andan outward wall 38. The bottom wall 34 and sidewall 36 are positionedagainst adjoining panels 12. The outward wall 38 smoothes the transitionbetween the adjacent panels having a shape that is straight, convex orconcave. The corner mold 28 may be a ring shaped, triangularcross-sectioned body for mounting in a circular basin between thesidewalls 32 and the bottom 30. Alternatively, the corner mold 28 may bea plurality of forms having a triangular or other shape to provide asmooth transition between adjoining panels. The corner mold 28comprising straight sections adapted for mounting in a polygon-sidedbasin between the sidewalls 32 and the bottom 30 or between theadjoining sidewalls 32. The corner mold 28 can be made of foam, wood,metal, plastic or any material compatible with the elastomeric barriercoating material and substrate. The corner molds are placed in a desiredposition and sprayed with the third elastomer barrier layer 26 to holdthe mold in place as a part of the substrate and intermediate thebarrier coating 26 and the basin 10.

Referring to FIG. 3, the base 30 and the sidewalls 32 join atapproximately a right angle. The side panels 32 and bottom panels 30 arejoined at a break flange 40 formed at the edge 14 of each panel. Thecorner molds 28 are disposed between the adjoining panels and arepre-sealed 25 by an application of barrier coating material. The bottomwall 34 of the corner mold 28 is on the bottom 30 of the basin 10 andthe outside wall 38 faces into the basin 10. Inside wall 44 extendingalong the bottom 30 and sides 32 of the basin 10 defines the waterholding area with an open top 33. The corner molds 28 provide a roundededge for the bottom 30 of the basin 10 reducing the sharp corners andfor sloping from the walls 32 to the drain 74. The elastomeric barrier26 is applied to the inside wall 44, along the top flange 46 into eachpipe stub 47 and along the sides 32 and bottom 30. The elastomericbarrier 26 is applied to the basin 10 along the interior wall 44 of thesides 32 and the bottom 30 panels 12. The elastomeric barrier liner 26is sprayed or otherwise applied over the preferably still warm preseal25 applied to the seams 24 to form a multilayer homogenous third barrierlayer 26. The outside elastomeric barrier 26 is extended up along thesidewalls 32 and onto the mounting surface 45 of the top flange 46 toliner edge 48. Liner edge 48 is disposed outside the interior wall 44 ofthe basin 10 along the top flange 46 preferably outside the fastenerholes 18 on top flange 46. Link holes 50 are punched or drilled throughthe panels 12 from the inside 44 to the outside 54. It should beunderstood, the link hole 50 may alternatively be formed as a dent 84(FIG. 9) or indent on the panel 12. The dent 84 (FIG. 9) creating acontour on the inner surface 44 of the basin 10 to provide a mechanicallink between the barrier coating 26 and the panel 12.

Continuing to refer to FIG. 3, and referring to FIG. 4, the link 52 isformed through the link hole 50 ending in a button head shaped like aknob 62 on the outside 54 of the basin 10. The link hole 50 has a tiediameter d1 and extends from the inside 44 to the outside 54. The linkhole 50 is coated with the second layer organic powder 56, along theinner surface 58 of the hole. The barrier layer 26 flows through thelink hole 50 on application to the basin 10. The barrier layer 26 formsa tie 60 in the hole 50 and accumulates on the outside 54 of the basin10 in a knob 62. The knob 62 has a knob diameter d2 that is larger thanthe link hole 50 to resist being pulled through the link hole 50. Thelink hole 50 is coated with the second layer organic powder 56, alongthe inner surface 58 of the hole. The link hole 50 is sealed with theelastomeric barrier coating 26 on the inside 44 and by the knob 62 onthe outside 54.

Referring to FIG. 5, the connector pipe stub 47 is shown as attached tothe panel 12. The pipe stub 47 provides an attaching location for sourceand drain piping 67 at the installation site. The pipe stub 47 isattached to the panel 12 before application of the organic coating 56.The second layer organic powder coating is applied to the panelincluding around and on the pipe stub 47 to seal the ends, exterior anda portion of the interior of the stub 47 and the weld 49. The pipe stub47 has an inside end 51 and an outside end 53. The outside diameter 63and inside diameter 65 of the pipe stub 47 are chosen based on theapplication, flow rates and customer preference. The pipe stub 47 has aninside wall 55 and an outside wall 59. The pipe hole 61 in the panel 12is sized slightly larger than the outside diameter 63 to allow the pipestub 47 to be inserted into the pipe hole 61 to a position having theinside end 51 aligned with the inside surface 44 of the basin 10. Thepipe hole 61 in the panel is sized to allow the pipe stub 47 toconcentrically fit in the hole 61 for attachment. A weld 49 attaches thepipe stub 47 to the panel 12. The powder coating 56 is electrostaticallyapplied to evenly coat the entire panel pipe stub assembly including theweld 49 and provide a bonding surface for the elastomeric barriercoating 26. The elastomeric barrier 26 is applied to the inside 44 ofthe panel 12 and extended onto a portion of the inside wall 55 apredetermined distance 57 usually about 2 inches from the inside end 51.The liner edge 48 in the pipe stub 47 is spaced a predetermined distancefrom the outside end 53 to protect against over heating the barriercoating 26 when the pipe stub 47 is attached to facility piping 67 suchas by welding.

Referring to FIG. 6, the panels of the sidewall 32 are lined 15 with thefirst galvanizing layer 70, the second organic powder coating layer 56,and the third elastomeric barrier coating layer 26. The barrier coating26 extends up to the wall flange 46 and past the fastener 16 andfastener hole 18 to a position spaced from the basin 10 interior. Uppersection 64 may be a casing for housing heat transfer coils (not shown)having a sidewall 66 and bottom flange 148 for mateingly attaching tobasin sidewall 32. Upper section 64 is attached to basin 10 by aligningthe flanges 46, 146 and driving fasteners 16 there through. The fastener16 may penetrate the barrier coat 26 on the top flange 46. The barriercoating 26 extends intermediate the upper section 64 and the side wall32. The fastener 16 bears against the flange 46 and flange 68 tocompress barrier coating 26 there between. Sealer or a preseal 25 asdescribed above may also be used in this flange joint 24 to help sealthe joint. Fastener 16 is intermediate liner edge 46 and the interior ofbasin 10.

Continuing to refer to FIG. 6, the barrier coating 26 is applied alongthe interior 44 of the sidewall 32. Link holes 50 are positioned alongthe panel 12 especially at high action areas such as close to flowinterfaces, high traffic areas or where liquid is moving due to a pumpor circulating action. The link hole 50 extends through the wall 32, 30of the panel 12 to allow the elastomeric barrier coating 26 to flowthrough during application and form a button head 62 on the outsidesurface 54. The button head 62 is larger than link hole 50 to preventthe button head 62 from being pulled through the hole 50 The button headprovides a mechanical link to the panel 12 to promote the connection tothe underlying substrate 70 and to hold the barrier coating 26 in placeand preserve the integrity of the barrier coating 26 in the basin 10 inthe event that the bond between the barrier coating 26 and the powdercoating 56 is broken. It should be understood, the outside third layerof an elastomeric material is a barrier coating 26 when properly appliedand cured becomes an integral inner surface of the basin 10. The barriercoating 26 having its liner edge 46 is mechanically bound by theattached flanges 46, 146 and is isolated from the basin contents.

Continuing to refer to FIG. 6, the pre-seal 25 over the seams 24 isseparately cured and bonded to the barrier coating 26 to becomehomogenously part of the elastomeric inner barrier coating 26. Thepre-seal 25 may also be applied over the corner mold 28. Corner mold 28is adapted to fit snugly in corner spaces or where two adjoining walls30, 32 meet. The corner mold 28 has an outer surface 38 adapted toprovide a smooth transition between the two adjoining walls 30, 32. Thecorner mold 28 may have a flat, convex or concave outer surface 38depending on the angle of intersection of the adjacent walls. The cornermold 28 is placed in the structure before the third layer elastomericbarrier coating 26 is applied to become an integral part of the basin10. The molds 28 become part of the substrate when covered by the lastbarrier coating coat 26. The barrier coating 26 on the bottom wall 30 isallowed to gravity cure so the resulting basin bottom 72 is flat orproperly sloped to a drain 74 (FIG. 5).

Referring to FIG. 7, the panel 12 comprises a steel plate 12 having afirst layer to resist corrosion of zinc 70 thus galvanizing the steelplate 12. The panels 12 are coated with a thermoset second layer 56comprising a powdered polymer coating electrostatically applied to bothsides 44, 54 and to the inner surfaces of the holes 18, 50 (FIG. 3),61(FIG. 5). A third barrier layer 26 is applied onto the thermoset layer56 forming an elastomeric barrier coating 26. The elastomeric barriercoating 26 is formed from a material such as polyurethane, polyurea, amixture of the two or similar sprayable material on the inside wall 44.The galvanized coating may be of a type well known in the art of coatedmetals. The organic powder coating 56 protects the inside surface 44 andoutside surface 54 of the panel 12 from contaminates and corrosiveelements and to provide a clean surface to bond to the elastomericbarrier coating 26. In the preferred embodiment a G235 type galvanizingon the panel works well. The powder coating 56 is an organic type ofcoating applied to the galvanized steel after it has been cleaned,rinsed and dried preferably using heat. The organic coating 56 isfavorably applied using an electrostatic spraying process to evenly coatand hold the powder coating to the galvanized metal 70. A thermoset cureis used to bond the organic coating to the galvanized substrate 12 bybaking at a predefined time and temperature predetermined by therequirements of the coating material. The second layer comprising anorganic powder coating electrostatically sprayed on the galvanizedsubstrate and baked to cure may be a material such as Coating Powderavailable from Rohm and Haas Canada, 2 Manse Road, West Hill, Ontario,M1E 3T9, Canada. The Rohm and Haas product is comprised of Calciummetasilicate having a weight percentage between 40 and 50%, an epoxyresin having a weight percentage of between 40 and 50% and titaniumdioxide having a weight percentage between 5 and 10%.

Continuing to refer to FIG. 7, the third layer elastomer barrier coating26 is an elastomeric coating such as a polyurethane, polyurea, ormixture of polyurethane and polyurea or other similar material appliedin a liquid form. The barrier coating 26 materials are pumped fromseparate containers into a two-component spray gun where the componentsare mixed, atomized and discharged from the gun (not shown). The barriercoating 26 may be a material such as TUFF STUFF or Durabond Polyurethaneboth available from Rhino Linings, USA, 9151 Rehco Road, San Diego,Calif. 92121. The Rhino Lining TUFF STUFF has two components comprisingan A component, isocyanate, part no. 60012 and B component resin, partno. 60021. The barrier coating 26 is applied by liquid form on the seams24 to pre-seal the joints between panels 12.

Referring to FIG. 8, the present invention is directed to a process forassembling and sealing a cooling tower, water basin or the like forholding water for cooling, evaporative or condensing processes. Theprocess comprises the steps of:

-   -   1. Forming panels 12 in reconfigured shapes and sizes from        galvanized steel panels having a type G-235 galvanized coating        to provide a first corrosion resistant layer and substrate for        subsequent coatings 70.    -   2. Modifying the panels 12 by bending flanges 46 and punching        fastener holes 18 in the flanges for interconnecting the panels        12. The fastener holes 18 formed in a predetermined pattern        spaced, from the edges of the panel.    -   3. Cutting link holes 50 by punching, drilling or other means in        the panel 12 to provide mechanical link 52 between the barrier        coating 26 and the panel 12.    -   4. Cutting source and drain holes in the panels at predetermined        locations. The holes are sized to receive the outside diameter        of the pipe stub therein.    -   5. Attaching source or drain pipe stubs concentrically into the        respective source and drain holes by inserting the pipe stub in        the respective hole having the inside end of the stub flush with        the inside surface 44 of the basin 10 and welding the stub in        place to sealingly attach the stub to the basin 10.    -   6. Cleaning the panels 12 by an acid type cleaning solution such        as phosphoric acid to remove contaminates.    -   7. Rinsing the panels 12 with water to remove the acid type        cleaner.    -   8. Rinsing the panels a second time to remove as much of the        acid solution as possible from the panels 12.    -   9. Drying the panels using heat to thoroughly dry the metal and        immediately thereafter,    -   10. Coating the panels including the inside and outside surface,        including any attached pipe stubs with an organic powder coating        such as, for example epoxy, polyester, acrylics or hybrids that        are homogenous and designed for application to metals, by        electrostatic spray on both sides of the panel especially around        the binding holes and edges to a typical thickness of 0.004        inches.    -   11. Baking the coated metal panels to cure or thermoset the        organic coating. The baking process performed in the preferred        embodiment at around 250-600 degrees Fahrenheit for 1 to 20        minutes depending on the coating and thickness of the steel.    -   12. Cooling the panels after curing.    -   13. Assembling the coated panels into sub assemblies as required        for shipping to the installation site.    -   14. Mixing any selected additives into the barrier coating        components for desired mechanical or chemical properties of the        barrier coating.    -   15. Sealing the seams between the panels 12 by application of a        liquid state barrier coating material directly over the seams.        The liquid barrier coating material pre-seals the seams and        prevents the barrier coating material from leaking through the        seams during the barrier coating application    -   16. Placing the forms, if desired, in the corners, between        adjacent panels and where sides meet to provide a smooth        transition between adjacent panels.    -   17. Spraying the elastomer barrier coating onto the inside of        the basin 10 to form a seamless barrier coating 26 on the        interior of the basin 10, including double spraying the seams        and any exposed fasteners and spraying into each pipe stub a        predetermined distance and along the vertical walls 32 of the        basin and along the mounting flange 46.    -   18. Curing the barrier coating by time, heat or other method.    -   19. Shipping the subassemblies to the assembly site for further        assembly of the unit structure.    -   20. Assembling the subassemblies together in a manner that        minimizes the exposure of the edge of the barrier coating to        water in the basin by capturing the liner 15 between adjacent        subassemblies.

Referring to FIG. 9, an upper section 64 having a sidewall 76 with abottom 78 and a bottom flange 146 may be pre assembled and mounted tothe basin 10 at the customer site. The upper section 64 may be a casing,which mount on the basins and typically have heat transfer coils and/orcooling tower fill therein. The upper section 64 may have an elastomericupper section barrier 126 on the inside surface 80. The elastomericbarrier 126 may extend outside the interior 82 of the structure 64 alonga bottom flange 146. As described above, the basin 10 has a single piecethree layer liner 26 along the inside wall 32 of the basin. The lineredges 48 are on the respective mounting flanges 46, 146. Fasteners 16extend through fastener holes 18 in the top and bottom flanges 46, 146and through the elastomeric barrier 26 to attach the basin 10 to theupper section 64. The fasteners are preferably intermediate the lineredge 48 and the interior of the basin 10. The edges 48, 148 respectivebarrier coatings 26 of the upper section 64 and the basin 10 aresealingly compressed along the junction of the mounting flanges 46, 146.In this way, the elastomeric barrier 26 is clamped between the assembledsub assemblies 10, 64 to prevent the barrier coating edge 48 fromexposure to the water in the basin 10. It should be understood, theupper section can be lined with the elastomeric barrier 26 or not. Inthe case that the upper section is not lined, the barrier coating of thebasin 10 is captured by the upper section 64 and the basin 10 joinedvertically having the liner edge 48 extending out onto the top flange 46and captured between the mating flanges 46 146. Alternatively, a flangering 71 or sealer may be used on top of the mounting flange 46 tosealingly isolate the liner edge 48.

In use, the basin is formed from prepared steel panels 12 made ofgalvanized steel with a zinc coating 70 thereon. The first protectivelayer is zinc applied during the galvanizing process. The secondprotective layer 56 is an organic powder electrostatically applied andcured on top of the zinc 70. Applying the organic powder coating 56provides a clean dry surface and enhance the adhesion of the barriercoating 26 to the basin 10 also seals and protects the galvanized steelpanels. The panels 12 are assembled into a basin 10 or other substructure for holding water or liquid and other subassemblies are alsoassembled. The third protective layer comprising an elastomer materialis sprayed on the basin 10. The elastomer barrier coating 26 material isapplied first in liquid form to the seams 24, and joints and areasaround the connecting pipes 47 to preseal 25 those areas. The thirdlayer elastomeric barrier coating 26 is then applied by spraying thesame or different multi-part elastomer material evenly over the entireinner surface 44 of the basin 10 to form a contiguous coating 26 overthe entire interior surface of the basin 10 having the barrier coating26 extending up to and out of the top of the basin along the mountingflange 46. The barrier coating 26 should preferably be sprayed to aminimum thickness such that the pre-seal layers are covered, and theliner 15 is a uniform thickness forming a smooth interior surface acrossthe entire basin. The third elastomeric layer 26 is applied to a minimumis 1/16″ up to a preferred maximum of ⅛″. The third layer barriercoating 26 can be thicker to 1″ if the environment and liquid conditionsrequire this thickness of protection. The barrier coating 26 ispreferably extended above the maximum standing water level in the basin10 to isolate the liner edge 48 from the water.

After preparing the panels 12 by cutting, punching, bending and welding,the organic powder coating 56 is applied to both sides of each panel, onthe inside surface of the link holes 50 and over and inside the pipestubs 47 and their welded connection to the panel 12. The organiccoating 56 provides a fresh surface where the elastomeric barriercoating 26 adheres to the organic coating 56 better than adhering to thegalvanized 70 (FIG. 7) surface to secure the barrier coating 26 in placein the basin 10. The galvanized layer 70 (FIG. 7) and the organiccoating 56 provide a two coat bonding layer for the third coat elastomerbarrier coating 26. The zinc of the galvanizing 70 (FIG. 7) adheres verywell to the underlying steel panel 12, the organic powder coating 56 istightly bonded to the zinc coating 70 (FIG. 7) and the elastomer barriercoating 26 tightly bonds to the organic coating 56. The organic powdercoating 56 may be a coating like Baltibond® available from Baltimore AirCoil. Other organic powder coatings include powder coating such as, forexample, epoxy, polyester, acrylics or hybrids that are homogenous anddesigned for application to metals. An organic coating 56 having amicroscopically porous outer surface provides a mechanically bondingsite for the barrier coating material along with a chemical bondingmechanism. The barrier coating is applied in liquid form from the mixinggun (not shown) where the components are mixed, atomized allowing theliquid barrier coating to flow into the pores of the organic coating andmechanically and chemically bond the barrier coating 26 to the organiccoating 56.

The elastomer barrier coating 26 is preferably a two part polyurethanemixture. The multiple parts are mixed during the application process. Inthe present invention a spray gun is provided having inputs for each ofthe individual barrier coating components wherein the parts are mixed ata predetermined ratio while being atomized and propelled out of the gunat the nozzle to be applied to the surface of the vessel 10. Theelastomeric barrier coating 26 materials may also be polyurea or amixture of polyurea and polyurethane. It should also be understood thebarrier coating material may have additives to adjust the cure time,improve UV resistance, change impact, slip and chemical resistance, addcolor to the barrier coating, and improve fire retardancy, and increasedurability and traction among other attributes. Additional chemicals oraccelerants can be mixed with the barrier coating mixture to acceleratecure time. In the preferred environment the partial cure time or setuptime is calculated to be less than one minute to allow ongoing work onthe vessel 10 shortly after application of the elastomer barrier coating26, to reduce uneven application due to dripping, and allow multiplespray layers as in the pre-sealing of the seams of the basin. Additiveswith solvent properties to the organic bonding layer 56 may be added tothe elastomer barrier coating 12 materials to provide an additionalchemical bonding to the organic powder coating. Upon application theelastomer barrier coating material 12 would soften the outside surfaceof the organic coating causing a chemical mixture with the liquidbarrier coating material. Upon curing the two layers, organic coatingand barrier coating would be chemically bonded as well.

The elastomer third layer barrier coating 26 is applied to the insidewall 44 from the top flange 46 into each pipe stub 47 and along thesides 32 and bottom 30 and over the top flange 46 on the other side. Theelastomer barrier coating 26 is applied to the basin 10 along theinterior wall 44 of the sides 32 and the bottom 30 panels 12. Thebarrier coating 26 flows over the first coat preseal 25, applied to theseams 24 and fasteners 16, to form a multilayer homogenous barriercoating 26 sealing the seams 24 and protecting the substrate. Theelastomer barrier coating 26 is preferably applied before the pre-seal25 is fully set up to allow the maximum bonding between the barriercoating layer 26 and the preseal 25. The barrier coating 26 shouldpreferably be sprayed to a thickness such that the pre-seal layers arecovered, and the liner is a uniform thickness across the entire basin.The elastomer barrier coating is extended up along the sidewalls 32 andover mounting wall flange 46 to a point outside the basin wherepossible. The liner edge 48 is captured and compressed between the topflange 46 of the basin sub assembly and the bottom flange 148 of themating panel to prevent any chance of water attacking the edge bond tothe panel 12. Liner edge 48 is disposed outside the interior wall 44 ofthe basin 10 along the wall flange 46 between the fastener holes 18 andthe panel edge 14 but may extend out to the edge of the flange 46. Linkholes 50 are formed to extend through the panels 12 from the inside 44to the outside 54. During application, the elastomer barrier coating 26material flows out through the link holes 50 and forms a retaining knob62 adjacent the exterior wall 54 of the basin 10 creating a mechanicalbutton like link between the outer layer 54 and the inner layer 44wherein the button 62 cannot pull through the link hole 50 and therebyholds the barrier coating to the panel 12, filling the hole and forminga mechanical link to the panel and the elastomer barrier coating 26,while simultaneously increasing the bonding surface area for greateradhesion compared to a flat surface only. The tie 60 and the knob 62 areformed of the elastomeric material of the barrier layer 26 which flowsthrough the link hole 50 upon application of the barrier coating 26.

The vessel is filled with water usually treated with chemicals tocontrol water chemistry and to prevent biological growth and circulatedin the system for cooling or heat transfer, etc. The barrier coatingprotects the metal structure and seals the seams and link holes tocontain the water and protect the steel panels. The seams 25 and linkholes 50 provide a tattletale status of a leak or water seeping behindthe barrier coating and next to the panel 12. If a rip or fault in thebarrier coating 26 allows water between the barrier coating and thebasin substrate, the water will seep out of the seam or link hole toindicate a problem with the barrier coating. This early indicator mayallow repair of the barrier coating before corrosive damage happens tothe underlying structural panel.

Although the invention has been described above in connection withparticular embodiments and examples, it will be appreciated by thoseskilled in the art that the invention is not necessarily so limited, andthat numerous other embodiments, examples, uses, modifications anddepartures from the embodiments, examples and uses are intended to beencompassed by the claims attached hereto. The entire disclosure of eachpatent and publication cited herein is incorporated by reference, as ifeach such patent or publication were individually incorporated byreference herein.

1. A multi-layer liner for use on a basin, the basin comprising aplurality of interconnected steel panels, the panels connected togetherforming a bottom, a top and sidewalls of the basin, the sidewalls havingan inside and an outside, the inside of the sidewalls and the bottomdefining an interior of the basin, seams between the panels, the linercomprising: a first galvanizing layer of zinc on the steel panels; athermoset layer of an organic coating on the first galvanizing layer,the organic coating comprising a powder coating electrostaticallyapplied to the surface of each of the plurality of plates; a preseal onthe seams, the preseal comprising an elastomer liner material applied inliquid form to the seams; a barrier coating mechanically linked to thebasin, the barrier coating on the interior of the basin, the barriercoating comprising an elastomer material, the elastomer material bondingto the organic coating along the interior portion of the basin, whereinzinc attaches to the steel panels, the organic coating bonds to the zincand the barrier coating bonds to the organic coating and the preseal toform a three layer liner on the basin.
 2. The invention of claim 1further comprising a link between the barrier coating and the basin, thelink comprising a tie, a link hole and a knob, the link hole formed inone of the plurality of panels, the link hole having a tie diameter, thetie on the barrier coating and extending through the link hole, the knobon the outside of the basin adjacent the link hole, the knob on the tie,the knob having a knob diameter larger than the link hole whereby theknob resists being pulled through the link hole linking the barrierlayer to the basin.
 3. The invention of claim 1 further comprising apipe connection on the basin, the pipe connection comprising a pipe stubhaving an inside end, an outside end, an inside wall and an outsidewall, the basin further comprising a pipe hole, the pipe stubconcentrically mounted in the pipe hole having the inside end flush withthe inside of the basin, the thermoset layer on the pipe connection, thebarrier layer on the inside end and a portion of the inside wall.
 4. Theinvention of claim 1 wherein the elastomer material is selected from agroup consisting of polyurethane, polyurea and a polyurethane/polyureamixture.
 5. The invention of claim 1 further comprising an uppersection, the basin further comprising a top flange on the top of thebasin, the upper section comprising side walls having a bottom, a bottomflange on the bottom, the barrier coating on the top flange, the barriercoating having a liner edge, the liner edge between the top flange andthe bottom flange.
 6. The invention of claim 5 further comprising apowder coating on the upper section, an elastomeric liner on the powdercoating on the upper section, the elastomer liner on the inner surfaceof the upper section and the bottom flange whereby the elastomeric linerand the barrier coating on the basin are clamped between the top flangeand the bottom flange.
 7. The invention of claim 1 further comprising acorner mold, the corner mold comprising a bottom wall, a side wall and ainterior wall, the corner mold disposed in the basin adjacent adjoiningpanels having the bottom wall on the bottom of the basin, the cornermold sidewall adjacent the wall of the basin, the corner moldintermediate the basin and the barrier coating.
 8. The invention ofclaim 5 further comprising a plurality of fastener holes on the topflange intermediate the liner edge and the side wall, the bottom flangefurther comprising a plurality of fastener holes mateingly aligned tothe fasteners holes in the basing mounting flange, a fastener in one ofthe plurality of fastener holes in the top flange and extending throughan aligned fastener hole in the bottom flange, the fastener penetratingthrough the barrier coating on the top flange.
 9. The invention of claim1 wherein the barrier coating is a two part elastomer having additivesmixed therein to give the barrier coating a quality selected from thegroup consisting of abrasion, color, Ultra Violet light resistance, fireresistance, chemical resistance, slip resistance, cure time adjustment,and durability,
 10. The invention of claim 2 further comprising a cornermold disposed between the sidewalls and the bottom of the basinintermediate the barrier coating and an adjacent panel.
 11. Theinvention of claim 2 wherein each basin panel further comprises a topflange adjacent the top of the basin, the barrier coating forming a onepiece liner layer on the inside of the basin and extending onto the topflange, the barrier coating having a liner edge on the top flange, anupper section having a bottom flange mounted on and attached to the topflange, the barrier coating liner edge between the top flange and thebottom flange, whereby the liner edge is clamped between the top flangeon the basin and the bottom flange on the upper section to isolate theliner edge from an interior of the basin.
 12. The invention of claim 11further comprising a corner mold disposed between the sidewalls and thebottom of the basin intermediate the liner and the panels.
 13. Theinvention of claim 3 further comprising a tie between the basin and thebarrier layer, the tie hole formed in one of the plurality of panels,the third protective coating further comprising a link extending intothe link hole whereby the third protective coating is mechanically andchemically bonded to the panel adjacent the link hole.
 14. The inventionof claim 2 wherein the link hole further comprises a link hole in one ofthe plurality of panels, the link hole extending through the sidewall ofthe basin, a tie on the barrier coating extending through the panel atthe link hole.
 15. The invention of claim 6 further comprising amechanical link between the barrier coating and the basin, the linkcomprising a tie, a link hole, the link hole formed in the interior wallof the basin, the tie extending from the barrier coating into the linkhole, the link hole having a tie diameter, the tie on the barriercoating and extending through the link hole whereby the link hole issealed and the tie binds the barrier layer to the basin.
 16. A liner foruse on a basin, the basin comprising a plurality of panelsinterconnected to form a bottom, an inside sidewall, and a top flange, aseam between adjoining panels, the liner comprising: a link hole in oneof the plurality of panels, the link hole extending from the inside ofthe liner to the outside of the basin; a galvanizing zinc layer on eachof the panels; a connection pipe on the basin, the connection pipeconcentrically mounted in a pipe hole cut in the panel, the connectionpipe having an inside end and an inside wall, inside end aligned withthe inside sidewall of the basin; a thermoset organic layer on the zinccoating each panel and covering each connection pipe, the organiccoating comprising a powder coating electrostatically applied to thesurface of each of the plurality of plates; a preseal on the seams, thepreseal comprising an elastomer liner material applied in liquid form tothe seams, the elastomer material solidifying after a cure time; abarrier coating on the interior of the basin, the barrier coatingcomprising an elastomer material, the barrier coating bonding onto theorganic coating along the interior portion of the basin and the presealliner material, a tie extending from the barrier coating through thelink hole, a knob in the tie adjacent the link hole, the basinintermediate the barrier coating and the knob.
 17. The invention ofclaim 16 the barrier coating further comprising a liner edge on the topflange, an upper section on the basin, the upper section having a bottomflange connected to the top flange, the liner edge captured between thetop flange and the bottom flange.
 18. The invention of claim 17 furthercomprising a corner mold, the corner mold having a bottom wall on thebasin bottom, a side wall on the basin side, the corner moldintermediate the barrier coating and the basin whereby the transitionbetween the sidewall and the bottom is smoothed by the corner mold. 19.A method of applying a liner to a basin to protect the underlyinggalvanized panels from corrosion in a wet environment, the galvanizedpanels assembled to form a basin having an interior configured forholding liquid, the basin having a plurality of seams between adjoiningpanels, the basin having an interior, a bottom, a top, a sidewall and atop flange adjacent the top, a mounting surface on the mounting flange,the method comprising the following steps: Modifying the panels ofgalvanized steel for assembly into a basin; Forming a link hole in oneof the panels; Cleaning the panels to remove oil, dirt andcontamination; Applying a powdered organic coating to the surface ofeach panel by electrostatic spray; Curing the powdered organic coating;Applying a preseal comprising a liquid elastomer to the seams; Applyinga barrier coating on the organic coating and the preseal the bariercoating comprising an elastomer compound compatible with the preseal.The barrier coating on the inside of the basin including the mountingsurface forming a one-piece liner from the bottom of the basin to themounting surface;
 20. The method of claim 19 wherein the spraying stepsfurther comprising double spraying the seams in the basin.
 21. Themethod of claim 20 wherein the method includes the step between thecuring and applying the liquid elastomer the step of: sanding thesurface of the basin and wiping the surface of the basin to be coatedwith the third elastomer spray liner with a cleaning solution.
 22. Themethod of claim 20 wherein the method includes the step between thecuring and applying the liquid elastomer the step of: prepping the basinand the elastomer application equipment to apply and spray while thebasin is still clean and warm from the cure step.